Advances in semiconductor fabrication technologies, and the corresponding increase in transistor counts achievable within a commercially practicable integrated circuit device, have opened the door to extreme levels of functional integration. Examples include system-on-a-chip (SOC) and system-on-a-programmable-chip (SOPC's) designs. The scale of such integration can, in certain respects, however, meet diminishing returns. New approaches to intra-block and inter-block circuit interface and interaction can extend the benefit that such large scale integration has the potential to offer.